Less inflammable hydraulic fluid



ing.

Patented Jan. 29, 1952 2,583,588 LESS INFLAMMABLE HYDRAULIC FLUID James Calvin Mosteller, Fair-field, Ohio No Drawing. Application June 8, 1949,

Serial No. 97,931

d 1 Claim. ((1252 78) (Granted under the act of March 3, 1883, as

AN-O-366 entitled Hydraulic Fluid, Petroleum" Base.

One object of the invention is to provide an oil which is substantially fireproof as measured by the tests of Air Force-Navy specification 3150" in regard to flammability.

Another object is to provide a fluid which will function both at -67 F. and at 250 F. or higher.

Another object is to provide a fluid which will have a good viscosity, i. e. that the fluid will be neither too thick nor too thin at the above extremes of temperatureto act as a good lubricant on mechanical parts with which it designedlyv comes into contact.

Another object is to provide a formulation of ingredients according to which a perfect solution is obtained 50 that no precipitation or other separation of ingredients occurs even at the named temperature extremes.

Another object is to provide a formulation which is nontoxic and not nauseating or irritat- Another object is to provide a fluid which will not have any undue swelling action on the various kinds of synthetic rubber used in aircraft hydraulic systems.

Another object is to provide a fluid of the above characteristics in which a viscosity-improver of especially desirable characteristics, i; e. polymerized di-octyl methyl methacrylate, hereinaiter referred to as Acryloid, is incorporated.

The addition of a lower-boiling fluorine-containing organic compound, which is a feature of amended April 30, 1928; 370 O. G. 757) This dilemma cannot be solved by leaving out the lower-boiling fluorine-containing organic compound if high fire resistance is to be a property of the resulting fluid. Fluorine-containing compounds, especially the lower boiling organic compounds have valuable properties as snuffers of combustion. This class of compounds comprises liquids which are non-flammable of themselves and when containedin an aircrafthydraulic fluid and exposed to a heated surface or fire will vaporize sooner than themineral 011 com ponent. Due tothe high density of the fluorine containing compound, its vapors will cover the heated surface or fire sufliciently to prevent enough oxygen coming in contact with the base oil to cause ignition of the oil, and in many cases will extinguish a flre whch is already in progress. I am aware of United States Patent 2,449,631 to Zimmer et al., which aims to produce a hydraulic oil of somewhat similar characteristics. Oil which is the subject of that patent contains a polymer of tri-fluoroe'thylene, which is one of the present inventors ingredients. The present invention is however an improvement on the Zimmer et al. invention, because it is impossible for Zimmer et al. to incorporate the highly desirable Acryloid in their composition due to the lack of a master solvent. As an example of my invention, I shall describe the preparation of a less inflammable hydraulic fluid by the use oi. the following formulation? 25 to 35% by weight, tetra-chloro-tetra-fluoropropane or equivalent 15 to 25% by weight,.mono-chloro-tri-fluoroethylene polymer (Fluorolube FS) 35 to 45% by weight, Voltesso 36 (Cetane) 7 to 13% by weight, Acryloid HF-855 6 to 10% by weight, XC,T" White Oil.

0.4% by weight, 2-6 di-tertiary-butyl, it-methyl phenol clic or straight chain compounds.

fincrease purposes. I d. A tri-fluoro-methyl group attached to the methyl phenol which is added after the complete mixture is obtained; the amount added being 0.4% calculated on the weight of the" complete mixture.

The function of the mono-chlorotri-fluoro-" ethylene polymer (Fluorolube FS) is that of a thickener of anon-flammability-conferring 4 ring; also an ethyl propyl or butyl group being perfluoro attached to ring. Also, a butoxy group containing no fluorine is required to be attached to the ring to enhance solubility.

Of the straight chain compounds, the suitable members are parafiins containing:

a. At least one-half of the hydrogens replaced by fluorine and the remaining ones replaced by chlorine.

b. At least one-half of the hydrogens replaced by chlorine and CFz groups adjacent to carbonchlorine groupsto enhancetheiv stability of the chlorine to hydrolysis.

0. At least one-half of the hydrogens replaced by a halogen of which at least three are fluorine atoms and'iatcleast two are chlorine atoms per agent. It also imparts properties and assists in conferring lubricating and shear-breakdownresisting properties and a high boilingpoint.

The function of the tetra-chloro-tetra-fluoropropane or equivalent is both that of a master solvent and of a fire proofing agent. Its boiling point is materially less than that ofthe-monochlorotrifluoro-ethylene polymer. As regards the latter, it .is to be noted that there are over 100 degreesof polymerizationpossible. I use the polymer fraction having a, boiling. point range between the temperatures 70? C. and

100 C. at lmm. pressure and a specific gravity of 1.94. at C. Unless this particular fraction is employed, most of. the usefuleffect of the ingredient will belost andthe fluid will not have .the properties that I seek. Zimmer et a1. do

not mention which polymers they employ.

The boiling point governs the degree of viscosity improvement to be expected, i. e. the

higher the boiling point, the greater the viscosity improvement and the less the fire-extinguishing quality.

The specific lower-boiling fluorinecontaining organic compound that I have mentioned has numerous equivalents. The equivalents may be as I- have ascertainedby experiment, either cy- One characteristic of the satisfactory cyclic compounds is that they all have at least one tri-fluoromethyl substituent attached directly to the henzene ring and that they also contain at least 'chlorine atom similarly-attached. The reason for the requirement of chlorine-fluorine groups a. To extend the liquidrange. y. b. To; obtain a solubility with hydrocarbons,

also with Fluorolube F. SJ and Acryloid H.

The satisfactory cyclic .compoundstmayjhave two tri-fluoro-methyl groups attached. to the benzene ring and at least two chlorine atoms also directly attached to the ring.

. c. A tri-fiuoro-methylflgroup may also be attached'to the ring also an ethyl or propyl or butyl group attached to the ring and containing halogen atoms replacing all of the hydrogens. If chlorine is the halogen used, then .fiuorine (CFz or CF'a groups) must be present to enhance stability of the chlorine-containing group. Itis desirable to leave at least one chlorine atom attached to the group, also at least one chlorine atom attached to the benzene ring for solubility- Dichlorobis (trifiuoromethyl)- -benzene m le.

" Specificallyfthe lower boiling fluorine containingchloro'ehydro-carbons which I may use as combination fire proofing agents and master solvents are by name:

Tetrachlorotetrafluoropropane F(3-}JJ(]3F N 31 l-i 4 Chloro l-3 bis (trifiuoroniethyll tenze'hej Cl o- F;

Butoxy l (pentafiuoroethyl) 4 (trifluorc- -methyl) benzene r l 1 Theforrn'ulae given are" suggestive only because the exact constitution of many of the deriv'a'tives'is still unknown. Thisiimcertainty is indicated by showing the bond from thesubs'tituentof a benzene ring entering 'the'side of the ring instead of attaching toa corner asis conventional. l

It is to be understood that'in the following 'claim'ther term. an: equivalent; of tetra-chlorotetra fiuoro propane"; I isintended to ,includ tetra-chloro-tetra-fluoro propane itself.

What I claim is:

A homogeneous composition of matter suitable for use as a hydraulic fluid, comprising:

A polymer of mono-chloro-tri-fluore-ethylene having a specific gravity of 1.94 at 25 C A petroleum fraction of paraffinic and naphthenic constituents similar to cetane in molecular weight, volatility and.

By weight viscosity to 7% to 13% 6% to 10% JAMES CALVIN MOSTELLER.

REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Bruson Aug. 31, 1937 Plunkett Feb. 4, 1941 Gaylor May 11, 1943 Leland Mar. 23, 1948 Zimmer et a1 Sept. 21, 1948 

